Production of lead free gasoline

ABSTRACT

PRODUCTION OF LEAD FREE GASOLINE IS DESCRIBED BY THE PROCESS COMBINATION OF REFORMING, AROMATIC RECOVERY AND ISOMERIZATION ARRANGED TO ISOLATE AMONG OTHER THINGS C6 HYDROCARBONS UPGRADED TO A HIGHER OCTANE PROCUCT BY ISOMERIZATION THEREBY CONTRIBUTIONG TO THE YIELD OF ACCEPTABLE OCTANE PRODUCT FOR BLENDING WITH REFORMATE PRODUCT.

United States Patent O 3,649,520 PRODUCTION OF LEAD FREE GASOLINE Richard G. Graven, Westrnont, N.J., assignor to Mobil Oil Corporation Filed Mar. 13, 1970, Ser. No. 19,174 Int. Cl. Cg 39/00 US. Cl. 208-93 3 Claims ABSTRACT OF THE DISCLOSURE Production of lead free gasoline is described by the process combination of reforming, aromatic recovery and isomerization arranged to isolate among other things C hydrocarbons upgraded to a higher octane product by isomerization thereby contributing to the yield of acceptable octane product for blending with reformate product.

BACKGROUND OF THE INVENTION The present invention is concerned with the production of gasoline. In particular the present invention is concerned with a novel method and arrangement of known processing steps for producing lead-free gasoline. The need for providing a lead free gasoline product has been prompted in recent years by air pollution problems confronting sections of the world employing combustion engines in relatively high density. Therefore the greatest application of lead-free gasoline will be in those areas of high automobile density where the presence of lead additive' combustion products are considered harmful and a major contributor to atmospheric pollution. Thus it is predictable that both relatively low and high octane gasoline products free of lead additives or other additives contributing to air pollution will be required in the near and/or immediate future to meet certain government restrictions and demands, on the one hand, while fulfilling the demands of the public and automobile manufacturers on the other hand. Thus the present invention is concerned with identifying a processing scheme compatible with present processing technology and/ or refinery installations, one might employ to upgrade relatively low octane gasoline material to an acceptable higher octane product suitable for use in a combustion engine known today and for the immediate future. Some patents of interest in producing unleaded gasoline are US. Pats. 2,905,619, 3,165,461 and 2,900,323.

SUMMARY OF THE INVENTION .The present invention is directed to upgrading low octane gasoline boiling range constituents to a higher octane gasoline product. In a particular aspect it is concerned with upgrading C hydrocarbon constituents suitable for blending with higher octane gasoline product of reform ing. In yet another aspect the present invention is con- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 identifies an arrangement of processing steps effective for upgrading naphtha or gasoline boiling range materials ina sequence of processing steps which includes 3,649,520 Patented Mar. 14, 1972 ice reforming C hydrocarbons, aromatics recovery, isomerization and fractionation steps which are particularly effective for isolating and upgrading C hydrocarbon components of low octane rating to higher octane constituents.

FIG. 2 identifies diagrammatically a block flow refinery process arrangement for upgrading crude oil to premium and regular gasoline product by a combination of refinery operations which includes the specific arrangement of FIG. 1.

DESCRIPTION OF SPECIFIC EMBODIMENTS In accordance with the present invention and diagrammatically represented in the attached drawing, a gasoline boiling range hydrocarbon fraction boiling in the range of from about C hydrocarbons up to about 380 F. and ob tained as straight run naphtha, coker naphtha or gasoline and in some cases catalytic-ally cracked or hydrocracked gasoline is introduced to the process by way of line 2 for passage to catalytic pretreatment such as desulfurization or denitrogenation in zone 4. In the catalytic pretreatment of zone 4 the gasoline charge is subjected to hydrogenation for the purpose of removing sulfur, nitrogen and any other undesired constituents or contaminants found in the gasoline charge. The pretreated gasoline is thereafter passed by line 6 to a separator vessel 8 referred to herein as a dehexanizer tower 8 maintained under temperature and pressure conditions designed to separate and permit recovery from the upper portion thereof hydrocarbon boiling 180 F. and lower boiling by line 1-0. Higher boiling gasoline hydrocarbons and boiling from about 180 F. up to about 380 F. and identified as stream B, in Table 1, are withdrawn from the bottom of dehexanizer 8 by line 12. It is, of course, recognized that a relatively rough separation may be made in dehaxanizer 8 and thus an amount of C hydrocarbons may be carried overhead and/or a portion of C hydrocarbons may withdraw from the bottom along with the intended higher boiling hydrocarbons.

The hydrocarbons in stream B and withdrawn by line 12 are thereafter passed to a reforming operation 14 wherein they are subjected to contact with a platinum catalyst in a catalytic reforming operation maintained under conditions selected to upgrade the gasoline and naphtha charge boiling above 180 F. to a higher octane product. In this reforming step the operating conditions of temperature, pressure and space velocity will be selected to produce reformate product thereof having a clear octane rating in the range of from about up to about 106 and preferably at least about 97 octane rating clear. In some special circumstances, particularly for the production of high octane unleaded gasoline, the reforming severity conditions may be selected to provide a product having an octane rating of at least 103 and preferably 104 octane rating clear. The reforming operation pursued will normally be a relatively sophisticated reforming operation to take advantage of presently known technology. The use of naphthene rich gasoline charge materials may be successfully employed; however with a parafiin rich feed, the hexane upgrading concept of this invention will be even more advantageous. It is to be understood that reforming step 14 may be a regenerative or semi-regenreative operation. The efiluent of reforming step 14 is normally separated to recover a hydrogen rich gas from the remaining efiluent in equipment not shown-and which can be used in other parts of the process such as in a hydrogenation step or an isomerization step hereinafter discussed. This recovery apparatus for hydrogen rich gas and circulation in the system is not specifically shown in the drawing since use of such hydrogen rich gas streams is generally known in the prior art. The reformate product from which hydrogen rich gas has been recovered is thereafter passed by line 16 to separator tower 18 known as a depentanizer. In depentanizer tower 18 the operating conditions are selected and maintained to effect separation and recovery of C and any remaining lower boiling hydrocarbons from a reformate product effluent stream boiling above about C hydrocarbons. The composition of the reformate product in line 22 is identified in Table 3 and comprises about 65% aromatics. The C and lower boiling hydrocarbons are removed from the top of tower 18 by line 20 for further processing as desired and generally known in the prior art. The reformate product boiling above C hydrocarbons are withdrawn from the bottom of depentanizer 18 by line 22. Since an important aspect of the processing sequence is to concentrate low octane C hydrocarbons, some C hydrocarbons may be withdrawn from the bottom of tower 18 by line 22. The higher boiling reformate fraction obtained from depentanizer 18, such as identified in Table 3, is passed by line 22 to a dehexanizer tower 24 wherein the conditions of operation are selected to provide a cut point in the range of 158 F. up to about 225 F. so as to separate an overhead fraction primarily comprising hydrocarbons boiling in the range of C hydrocarbons to a cut point of from about 150 F. up to about 200 or 225 F. from a higher boiling reformate product fraction boiling above the selected cut point. The influence of the cut point selected for tower 24 upon the product can be clearly seen by reference to Table 4. Reformate product in line 26 having the composition identified in Table 4 is withdrawn from the bottom of tower 24 by line 26. This reformate product material being a relatively high octane product material thus may be utilized as the premium gasoline in unleaded form. The lower boiling material recovered from tower 24 by line 28 and having the composition of stream C, Table 4, is removed as an overhead fraction for further processing as hereinafter described. This recovered hydrocarbon fraction in line 28 comprises primarily the isolated C hydrocarbons of relatively low octane and C hydrocarbons of varying amount depending upon the cut point selected needs to be converted to higher octane product in order to be used in an unleaded gasoline product. When employing a cut point of about 225 F. in tower 24, more C7 hydrocarbons will be carried overhead thereby considerably upgrading the product in line 26 as evidenced by the data of Table 4. The C hydrocarbon thus thrown ovehead may be recovered from the process by tower 56 discussed below. The C hydrocarbons thus separated and recovered may be further processed such as by reforming, shape selective cracking or converted to olefin product as by fluid catalytic cracking or thermal cracking.

The light hydrocarbon fraction recovered as overhead from dehexanizer 8 by line and which may contain a small amount of C hydrocarbons may be combined with the C and lighter hydrocarbons recovered from depentanizer 18 or separately processed. The C and lighter hydrocarbons in line 10 are thereafter debutanized and depentanized in the sequence of separation steps hereinafter briefly discussed. The C hydrocarbons and lighter fraction thus recovered are initially passed to debutanizer 30 wherein C and lighter hydrocarbons are separated from higher boiling hydrocarbons to permit recovery thereof from the upper portion of the tower by line 32 with the remaining higher boiling portion being withdrawn from the bottom of debutanizer 30 and passed by line 34 to a depentanizer tower 36. In depentanizer tower 36, C hydrocarbons are separated and removed from the upper portion thereof by line 38 with the remaining C and higher boiling hydrocarbons being withdrawn from the bottom of depentaizer tower 36 by line 40. The sequence above described, provides a hydrocarbon stream rich in C hydrocarbons for upgrading to higher octane product. The C rich hydrocarbon stream in line 40 and having the composition of stream A, Table 1, thereafter is passed to reforming step 42. The reforming operation contemplated in step 42 is primarily one of dehydrogenation for the purpose of converting C naphthenes to aromatics. Thus the octane rating of the product therefrom will depend considerably upon the type of C hydrocarbons in the charge thereto. It is clear, therefore, that reforming step 42 is operated under conditions which are particularly selective for effecting dehydrogenation of naphthenes to form aromatics and isomerization of isomerizable hydrocarbons. The reformate product efiiuent of reforming step 42 is separated in a separation zone not shown to recover a hydrogen rich gas stream from a higher boiling reformate product stream. The hydrogen rich gas stream is recycled to the process such as to the pretreating step, reforming step or isomerization step herein discussed. The reformate product freed of hydroggen rich gas is recovered from reforming step 42 and passed by line 44 to a depentanizer tower 46 wherein C and lower boiling hydrocarbons are separated from higher boiling reformate product or aromatic enriched stream with the C hydrocarbons recovered from the upper portion of the tower by line 48. These C and lower boiling hydrocarbons may thereafter be stabilized in suitable equipment not shown and processed as by isomerization. The aromatic enriched stream separated in depentanizer tower 46 is removed from the bottom thereof by line 50 and passed to an aromatics removal zone such as an extraction step 52. The aromatic rich stream in line 50 and identified in Table 2 is combined with the isolated C hydrocarbon stream in line 28. The combined C hydrocarbon stream is passed to the aromatic removal step 52. Step 52 is primarily for the removal of aromatics such as benzene, toluene and perhaps xylene from the combined C hydrocarbon stream. The aromatic separated in zone 52 as by extraction, molecular sieve adsorption or any other convenient method is withdrawn by line 54. The aromatic removal step may be substantially any aromatic removal step suitable for effecting an economic recovery of aromatics from the remaining C hydrocarbon components introduced thereto. The aromatic free hydrocarbons recovered from step 52 which may comprise some 0, hydrocarbons and a small amount of unremoved aromatics is thereafter fractionated when required to separate 0, hydrocarbons from the lower boiling C hydrocarbons. The C hydrocarbons are then passed by line 56 to hydrogenation step 58. Any separated C hydrocarbon may be recycled to the reforming steps herein discussed or processed in any desired manner. In hydrogenation step 58 aromatics remaining in the C hydrocarbons are hydrogenated and converted to naphthenes since it has been found that even a small amount of aromatics in the charge to the isomerization step is not particularly desirable. It is of course understood that hydrogen suitable for this hydrogenation step may be recovered from the hydrogen rich reformate product of reforming steps 14 and/or 42. The hydro genated C fraction freed of aromatics and C hydro carbons is thereafter passed by line 60 to isomerization step 6 2. The isomerization of hexane hydrocarbons to higher octane product is one requiring relatively strict operating conditions to avoid undesired cracking and low tempera tures in the range of 200 to 500 F. are known to favor the isomerization to the higher octane C hydrocarbon components. The production of 2,2-dimethylbutane having an octane rating clear of about 91.8 and which blends as if it had an octane rating of about is enhanced by low temperature isomerization. It is desirable to recover any formed 2,3-dimethylbutane having a clear octane rating of about 103.5. As a word of caution, it is important to the isomerization of C hydrocarbon constituents to minimize not only aromatics in the charge but also naphthenes and C1 hydrocarbons since such materials have an undesirable influence or effect upon the activity and selectivity of typical solid type isomerization catalyst. In the operation above discussed naphthenes may build up in the isomerization product stream and care should be taken to prevent this from happening. Therefore, the product is isomerization obtained in step 62 is passed by line 64 to a C splitter tower 66. Splitter tower 66 is operated under conditions to permit the recovery of 2,2-dimethylbutane or neohexane overhead therefrom by line 68. C hyrdrocarbons not isomerized in step 62 are withdrawn from a lower portion of the tower by line 70 essentially as a recycle stream for recycle to step 62 or step 42. The C hydrocarbons may be recycled to the isomerization step all or in part, it being important, however, to limit the build up of naphthenes in this C recycle stream because of their undesirable influence on the isomerization step. To prevent this undesired build-up of naphthenes, a naphthene bleed stream 74 is used to pass a portion of this recycle stream to reformer 42 or 14 or separator tower 56. The processing scheme thus described eliminates low octane C hydrocarbon which may be converted to other products such as by shape selective cracking, fluid cracking and in some cases these hydrocarbons may be cyclized in a very selective low pressure reforming operation.

It is immediately clear from the above that the processing scheme specifically discussed above is a most effective processing arrangement for upgrading gasoline material and particularly relatively low octane C hydrocarbons found in the gasoline boiling range. Furthermore, the

processing arrangement above discussed results in the production of relatively high octane components from the reforming and isomerization steps which can be blended to suit the refiner in his desired to provide gasoline products which will meet the octane rating standards suitable to provide regularand premium gasoline products having an octane rating of at least 90 clear up to 104 or 106 octane rating clear.

The reforming steps employed in the processing sequence of this invention preferably employ catalyst components comprising platinum and/or platinum-type com pound dispersed on alumina. Bimetallic reforming catalysts may also be employed to considerable advantage and the amount of platinum required in the catalyst will be less than that required when platinum is used alone. It is to be understood that the catalyst may be halogen promoted and every suitable operating variable such as moisture control and cracking inhibitors known in the prior art may be called upon to enhance the reforming operation in the direction of optimizing the production of desired octane product. The reforming operation may be effected at temperatures selected from within the range of from about 800 F. up to about 1050 F. under conditions of pressure in the range of from about 100 p.s.i.g. I u to about 1000 p.s.i.g. and prefer-ably not more than about 500 p.s.i.g. Generally the pressure will be selected from within the range of from about 200 p.s.i.g. up to about 500 p.s.i.g. The space velocity on a liquid hourly basis may be in the range of from about 0.5 up to about 10in the presence of hydrogen at mol ratios known in 'the art. As stated hereinbefore the reforming operation may be semi-regenerative or a regenerative operation wherein regeneration of the catalyst occurs quite frequently and requires the use of an extra reactor in the reforming sequence known as a swing reactor. In any event the upgrading of C hydrocarbons and hydrocarbons boiling above C hydrocarbons such as C7+ hydrocarbons are articularly effected in a combination of separate reforming operations and the combination of reforming steps are employed in combination with an isomerization operation designed to particularly upgrade low octane C hydrocarbon constituents. Isomerization step 62 may be substantially any of the known isomerization processes of the priorart which will be effective for upgrading C hydrocarbon constituents. The isomerization catalysts employed may be either solid isomerization catalysts or ones which require a liquid phase operation. The extraction step for recovery of aromatics may also be substantially any known-method for effecting such separation in an economic manner. For example, extraction may be by adsorption and in particular a selective adsorption with a crystalline zeolite of proper pore dimensions. The aromatic freed product may in one type of operation be recovered from the zeolite such as by stripping and thereafter passed to the isomerization step. An effective material for the stripping operation could be hydrogen rich gas recovered from the reforming step of the process since the presence of such hydrogen gas is desirable in the isomerization step.

It is to be understood that methods for preparing the naphtha charge to the process and boiling up to about 380 F. and provide for recovering a C hydrocarbon rich stream from a higher boiling hydrocarbon fraction may rely upon other fractioning processing arrangements for effecting stabilization of the naphtha charge and the recovery of C and C hydrocarbons. Furthermore, desulfurization and denitrogenation of the naphtha charge or fractions thereof may be accomplished as specifically shown in FIG. 1 or separate fractions such as the specific hydrocarbon charge to the separate reforming steps may be separately subjected to desulfurization treatment. For example, the product stream in line 6 of FIG. 1 recovered from pretreater 4 may pass through a separate stabilizer tower not shown for removal of C and lower boiling constituents before passage of the remaining pretreated charge to dehexanizer tower such as tower 8. In yet another arrangement the crude tower of the refining process may be relied upon to separate a hydrocarbon fraction boiling from about F. up to about 380 F. from a lower boiling C to 160 F. hydrocarbon fraction. The thus obtained fraction boiling above 160 F. may be passed to desulfurization before being reformed in a platinum reforming operation. A fraction boiling below about 160 F. may be recoverd from the crude tower and after stabilization thereof to recover C and C hydrocarbons therefrom, this hexane rich fraction may be separately desulfurized before effecting reforming thereof. In any of these arrangements the important consideration Within the concept of the present invention is to effect a separation of low octane C hydrocarbons from higher boiling gasoline constitutents so that each can be efliciently processed to a higher octane component thereby effecting a significant increse in overall product yield of desired higher octane product.

FIG. 2 identifies a block flow refinery arrangement for upgrading crude oil to premium and regular grade gasoline product. The specific processing arrangement of FIG. I discussed hereinbefore may be employed in the overall refining operation of FIG. 2. In the refining arrangement of FIG. 2, a crude oil is introduced to the process by line 1 for passage to an atmospheric crude tower and vacuum tower arrangement diagrammatically represented by block 2. The operation of an atmospheric crude tower as well as a vacuum tower is well known in petroleum processing and suitable combinations thereof which will provide the refinery feeds hereinafter discussed will be suitable for use in the processing scheme of the invention herein described. In this refinery arrangement a catalytic cracking feed stock is Withdrawn by line 5 from the crude tower. A charge stock suitable for hydrocracking is withdrawn by line 7. The charge stocks for a coking operation is withdrawn by line 9 and a naphtha charge suitable for platinum reforming is withdrawn by line 11. The gas'oil charge in line 5 and selected to be processed in a catalytic cracking unit such as a fluid catalytic cracking unit is passed to a catalytic cracker 13. Products of catalytic cracking such as obtained by fluid catalytic cracking are separated in suitable fractioning equipment notshownto permit the recovery of olefin products suitable for passage by line 15 to an alkylation unit represented by block 17. Higher boiling catalytic product material is passed by line 19 to a splitter tower 21 wherein a separation is made between light catalytic gasoline withdrawn overhead by line 23 from heavy catalytic gasoline withdrawn from the bottom thereof by line 25. In the arrangement of FIG. 2, the light catalytic gasoline obtained from the catalytic cracking operation is passed by line 23 to a regular gasoline pool represented by block 27. In addition the product of alkylation is passed by line 29 to regular gasoline pool 27. The heavy catalytic gasoline withdrawn by line maybe passed by line 31 to block 33 for effecting a shape selective cracking thereof or thermal upgrading to gasoline product. The material thus treated is passed by line 35 to regular gasoline pool 27. In addition heavy catalytic gasoline instead of going through the steps of block 33 may be passed by line 37 to a pretreating step such as pretreater 39 for upgrading as discussed herein. The hydrocarbon charge in line 7 and suitable for processing by hydrocracking is passed to hydrocracker 41 wherein the charge is converted to products including light hydrocracking gasoline withdrawn by line 43 and heavy hydrocracked naphtha withdrawn by line 45. The light hydrocracked gasoline product in line 43 is passed to hexane upgrading represented by block 47. The hydrocarbon charge in line 9 and suitable for conversion by coking such as a delayed coker is passed to coker 49. In the coking operation represented by block 49 the hydrocarbon charge is converted and a light coker gasoline is recoverd therefrom by line 51 with a high boiling product by line 53 which is suitable for further processing in a hydrocracker represented by 41. The coker gasoline in line 51 is passed to pretreating step 39. In the pretreting step 39 straight-run gasoline, coker gasoline, and heavy catalytic cracked gasoline, in combination with one another or separately, are treated under hydrogenation conditions to efiect desulfurization and denitrogenation of the charge where required. The gasoline charge is thus pretreated by hydrogenation and may be combined with heavy naphtha product of hydrocracking obtained from 41 and thereafter the combined charge is passed by line 55 to a platinum reforming operation represented by block 57. It is to be understood that the processing scheme of FIG. 1 may replace the processing arrangement represented by pretreater 39 and platinum reforming 57. In any event the product of platinum reforming obtained in 57 is thereafter passed by line 59 to a separator 61 wherein separation is made between a light reformate product and a heavy reformate product. The light reformate product is withdrawn by line 63 and passed to hexane upgrading 4,7. This, of course, is very much in the same manner but less detailed than that described in FIG. 1. The heavy reformate product depending upon the cut point of splitter 61 may be passed to either premium gasoline pool, regular gasoline pool or both in some cases. In one arrangement the heavy reformate product is passed by line 65 to regular gasoline pool 27 or by line 67 to premium gasoline pool 69. In the arrangement of FIG. 2, block 71 and identified as a gas plant is concerned with the refinery operation which effects the recovery 0.; hydrocarbons from pentanes and light straight-run naphtha. The C s are withdrawn by line 73, the pentanes by line 75 and the straight-run naphtha by line 77. The arrangement of FIG. 2 shows isomerization of pentanes in block 79, from which is recovered an isopentane material in line 81 for passage to premium and regular gasoline pools 69 and .27 respectively. The light straight-run naphtha in line 77 is passed to hexane upgrading 47 from which is recovered neohexane and aromatics by line 83 which may then be passed to either premium gasoline pool 69 or regular gasoline pool 27. It is thus seen from the above brief description that the production of premium and regular gasoline in significant quantities whether on a clear or leaded basis requires considerable processing knowhow and refinery equipment for efiecting catalytic upgrading steps, all of which are designed to upgrade particular constituents of the crude charged to the opera tion. It is also immediately clear from the discussion 8 herein before presented that any improvement one might make in yield of desired product is of considerable benefit to the refiner, as well as the product user. However, this takes on an added importance when one is concerned with the preparation of regular and premium gasoline products free of lead. Therefore the processing concept of this in vention is concerned with maximizing the yields of hydrocarbon constituents having an acceptable octane rating and the specific arrangements described and discussed represent one method for achieving this desired improve ment.

TABLE l.-PROPERTIES AND COMPOSITION OF NAPHTHA STREAMS Stream A, (Jo-180 F Stream B, TBP midl-380 F.. Fraction continent TB}? MCS Yield, volume percent of crude 4. 1 29. 8 Gravity, A PI 72. 5 56. 4 Specific gravlty 0. 6936 0. 7531 ASIM distillation, F;

IBP

TABLE 2 [Yields and composition of Cu reformate from p.s.i.g. Reiorm'm of Ctr-infill. TBP Mid-continent naphtha at 98 05 plus 3+3 N seven y Percent at- Weight 71. 0

Volume es. s

Co yields (based on Cs180 F. TBP S.R.)

Paraflins Olefins Naphthenes 0 Aromatics g 28. 5

Ct paraflins 25. 4

2-2 dlmethylbutane 2-3 dim ethylbutane. 2 methylpentane 3 methylpentane. N-hexane C7 parafiins 10. 9

2-2 dimethylpentane 2-3 dimethylp entane 3-3 dimethylpentane 2-3 dimethylpentane 2 methylhmrana 3 methylh mom a 3 ethylpentane N-heptane Total aromatics t 28. 5

Benzene. Toluene- Percent at- Volume Weight Cu yields (basedon-1S0-3801F. TBP MCS) Parsfiins CeP 2-2 dimethylbutsno 2-3 dimethylhutana- 2 methylpentana. 3 methylpentana.

N-hexane 2-2 dimethylpentane...

2-3 dimethylpentane 2 ruethylh PXRHA 3 methylhexane 3 ethylpenrnm N-heptane CsP .1 .1;

2-2-4 trimethylpentsne--. 223 trimethylpentane..-

3 methyl 3-ethylpentane: 2-2 dimethylh exane 2-3 dimethylhexane H H 9 9 PP. PPPPPPPPP P mmwcr-cn 2 methylheptane 3 methylheptane 4 methylheptana. 3 ethylhexane N-octane To1uene Ethylbemena O-xylena M-xylene- P-xy ena TABLE 4 Composition of CH-reiormate fractions split at 158 F. and 200 F'. (Ce+reformate from 350 p.s.i.g. reforming of ISO-380 F. TBP MOS naphtha at 102 Crl- R+3 ON severity)] Split A Split B Stream Stream Stream Stream C, Cr- 26, C, Cr- 26, Fraction 168 F. 158 F.+ 200 F. 200 F.+

Yields, percent volume of CH- reiormate 11. 7 83.3 21. 7 78. 3

Compositions; component,

percent volume:

Cr Parefiins 2, 2 dimethylbutane 2, 3 dimethylbutane. 2 methylpentana-.- 3 methylpentane-. N-hexane C1 parafilus 2, 2 dimethylpentaneflunu 2, 3 dimethylpentane 2, 4 dimethylpentane 3,3 dimethylpentana. 2 methylhexane 3 methylhexane N-hepta Monoolefins Benzene Total Split B Stream Stream C, Ca- 26, 200 F. 200 F.+

Fraction 0. 11. 4. 7 7. 8. 8 4. 4. 7 1. 1. 0 Naphthenes l. 0. 4

Aromatics 73. 4 80. 5

Benzene 2. 1 Toluene. 13. 24. 01-}- 32.

Total Properties:

Specific gravity 0. 6693 0. 8371 0. 6955 0. 8514 RVP, lbs 6.1 1.1 5. 1 0. 8 Octane ratings:

R O 67. 6 98.8 70. 8 101. 3 R+3 cc. TEL/USG 87. 6 103. 0 90. 0 104. 0

Having thus provided a general description of the method and process of this invention and defined a specific embodiment for practising the concept of the invention, it is understood that no undue restrictions are to be imposed by reason thereof except as defined in the appended claims.

I claim:

1. A method for upgrading gasoline product of coking, hydrocracking, catalytic cracking and straight run gasoline which comprises (a) desulfnrizing gasoline product obtained as by coking and straight run gasoline,

(b) separating a first C rich hydrocarbon fraction from a higher boiling gasoline fraction following said desulfurizing step,

(c) reforming said higher boiling gasoline fraction to provide a reformate product of improved octane rat- 111g,

(d) separating and recovering from said reformate product a product fraction having an initial boiling point in the range of 150 to about 225 F. from a second C rich hydrocarbon fraction,

(e) reforming said first C rich hydrocarbon fraction and separating aromatics therefrom after combining with said second C rich hydrocarbon fraction,

(f) hydrogenating the C hydrocarbons fraction after separation of aromatics and G, hydrocarbons therefrom but before effecting isomerization thereof and (g) combining product of said isomerization step having an octane rating in excess of with said reformate product having an initial boiling point in the range of F. up to about 225 F.

2. A method for upgrading straight run gasoline hydrocracked gasoline, coker and heavy gasoline product of catalytic cracking which comprises,

(a) separating and recovering from gasoline product of coking, catalytic and hydrocracke'd gasoline as well as straight run gasoline, a first C rich hydrocarbon stream from a higher boiling gasoline fraction comprising C, hydrocarbons,

(b) desulfurizing said gasoline boiling range hydrocarbons before or after the above separation step,

(c) reforming said higher boiling hydrocarbon fraction,

(d) separating product of reforming to recover a second C rich hydrocarbon stream from a higher boiling reformate having an initial boiling point in the range of 150 to about 225 F.,

(e) reforming said first C rich hydrocarbon stream and stabilizing the product thereof,

(f) combining stabilized C reformate product with the second Cg rich hydrocarbon stream and removing aromatic and entrained c -hydrocarbon therefrom to provide a stream rich in normal hexane,

(g) isomerizing said normal hexane rich stream under conditions to produce isomers'th'ereof having an octane rating above 90 on a clear basis and (h) passing aromatic products of said reforming steps and products of said isomerizing steps to regular and premium gasoline products for blending 'With gasoline product of catalytic cracking, alkylation, and pentane isomerization.

3. A method for upgrading gasoline fractions boiling in the range of C hydrocarbons up to about 380 F. which comprises (a) stabilizing and desulfurizing said gasoline fraction so as to recover a first hydrocarbon stream rich in C hydrocarbons from a second higher boiling hydrocarbon stream comprising C hydrocarbons,

(b) separately reforming said first and second hydrocarbon streams with a platinum-type reforming catalyst, under conditions, to produce aromatic rich reformate streams,

(0) recovering reformate product having an initial boiling point in the range of 150 to 225 F. as one prodnot of the process suitable for use in regular or premium grade gasoline,

12 (d) recovering C rich hydrocarbon materials from said reforming operationsand separating aromatics and C hydrocarbons therefrom to provide a hexane rrichstream, n ,v (e) hydrogenating any aromatics remaining in said hexane rich stream, 9 v i (f) isomerizing the hydrogenated hexane rich stream and (g) combining product of said isomerization step in said regular and premium gasoline pool.

7 References Cited I UNITED STATES PATENTS U.S. c1, x11. 2O862, 65, 79, so 

